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Fighting Gremlins - Electrical Cutoff at 1:30 am

Honestly, vague title because I'm unsure where to even begin. We've been parked for a few days in Yellowstone National Park in the US. Historically we run 5-6 days on batteries alone (setup details below). Recently I completed a solar setup that I 'thought' was working well, or maybe currently think so? I'm not sure. After 2 days of being parked at Yellowstone in a relatively shady spot and arriving with full SOC of 14.59V on the Battle Borns, 'something' tripped in the system and shut me down. The Multiplus had a low battery alarm, the BMV showed 57% and something like 13.35V. The SmartSolar controller said that the battery voltage had dropped to 9.12V which is obviously well below anything a LiFePo4 battery should ever see. This tripped the battery guard, took me a little bit to locate the failure, initially thought it was the transfer switch because I've had a few issues with that. The battery guard appeared to have done its' job, albeit at the cost of the battery guard as the only way I was able to restore power was to bypass it. No apparent temperature issues, outside temp was 84F and inside the trailer was probably 78ish. Batteries are inside, under the main bed.

Fast forward another 30ish hours, we went to bed and night temperatures drop fairly rapidly. Around 1:30 am my wife woke me saying it was too quiet, she couldn't hear the fridge running. Pulled up the BMV app, it wouldn't load. Checked the screen of the device itself and it was shut off. Inverter was completely off despite being in "ON" position. Silly me, left the multimeter at home so I didn't have a way to manually read the voltage. First thing this morning, we packed up and left Yellowstone to run some errands including buying a multimeter as well as dump/fill the Airstream. Once solar started kicking in around 8:30 am, we started getting some intermittent functionality of 12V users as one would expect. The BMV eventually turned itself back on with a voltage of 13.05V, so not "actually" a low voltage or even 0% SOC. Air temp was chilly last night but not "that" chilly considering the batteries are inside, outside was in the 45-50F range while we were probably 55-60F inside.


As we speak, we're in an RV park outside Yellowstone connected to shore power to get a full charge all over again, but more importantly for cell service to connect to you guys and try to troubleshoot something. I've attached some photos as well - apologies in advance for the kabalsalat! I've tried cleaning up a bit, but definitely have room for further improvement.


Just not even sure where to begin troubleshooting because readouts have been looking normal despite the weird events. Solar this morning was 50ish watts in our shady spot in Yellowstone, ramped up to 515 watts or so once the day got a bit later and we were outside the park. Currently plugged into shore power and charging batteries at 1200W. Are there additional historical logs I can pull from either the BMV or the SmartSolar? The app-based readouts are pretty basic.


A bit about my system overall:
2003 Airstream
960W renogy panels, 6 x 160W each hooked up in Series-parallel configuration (two sets of 3 panels in series, then paralleled into the MPPT)
800 Ah BattleBorn batteries, 8 x 100 Ah each

BGA-225 battery guard
Multiplus 12/3000/120-50 120v VE Bus

Victron SmartSolar Charge Controller (150V 45A Tr)

BMV-712

Go Power! TS-30 30 Amp Automatic Transfer Switch (shore power & battery charge primary, secondary is from the inverter)




MPPT - Solar Charge ControllerMultiPlus Quattro Inverter ChargerBMV Battery Monitor
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Quick update - after getting onto some wifi and reading more about the BGA-225, looks like it automatically reconnects above 13.3V. Since I was at about 13.09V when it triggered 2 days ago, I was unable to reset it. We're now at 13.64V so I have restored the wiring to the OPTION 1 configuration and things are continuing to work properly.


https://1t1pye1e13di20waq11old70-wpengine.netdna-ssl.com/wp-content/uploads/2019/01/BGA-225-Full-Wiring-Guide-r02.pdf

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Hello @OleSimo,

sorry but I can't help, because I understand to less of this specific setup. I wanted only to express, as German individual that I had really to laugh loud about the German expression Kabelsalat when you wrote: "I've attached some photos as well - apologies in advance for the kabalsalat! I've tried cleaning up a bit, but definitely have room for further improvement."

It looks like that the German expression "Kabelsalat" is a common used expression as well as "Kindergarten" - it is so interesting how international are all users here in this forum!

I keep my fingers crossed that your equipment is soon doing it's job as it should be and you can continue your travel without any problems!

Kind regards from Munich, Bavaria, Germany

DayAndNight

PS: In some of my installation sites, specially at home there is a lot of Kabelsalat, too! ;-)

I learned kabelsalat on this forum and it describes my situation flawlessly :) Thanks for the kind words!

Are the batteries wired up like that following the manufacturers instructions? I’m just wondering if your issue is that the first 2 batteries at the inverter end are getting a full charge and the others aren’t. To get a balanced output from your batteries I think you need to change the negative cables so they daisy chain the same as the positive cables. And then you need to take the 2 negative cables from the opposite end back up to the terminal blocks. Hope this makes sense? Also you need to keep the cables the same length so you don’t have a different resistance between your 2 banks of 4 batteries.

Looking at your battery bank the top row from left to right we’ll number 1,2,3,4. The bottom row from left to right 5,6,7,8. At the moment you have the red cables going to the terminal blocks from batteries 4 & 8. These 2 red cables need to be the same length, example 1 metre. Next daisy chain the negative terminals the same way you have done the positives and take the black cables from batteries 1 & 5 back to the terminal blocks. These 2 black cables need to be the same length, example 3 metres. Make all of the daisy chain cables the same length as well, example 300mm. This should give you a balanced battery bank. Before putting the whole system back together it would be a good idea to charge each battery individually so you are starting off with balanced batteries.

Or as an option where you don’t have to worry about balancing the 2 rows would be to rotate your batteries by 90 degrees and daisy chain all 8 batteries together and only have 1 red cable and 1 black cable at the terminal blocks. You’d still need to take the red and black cables from opposite ends of the bank and upsize the gauge of cable but then at least you won’t have balance issues.


I think you are right, the wiring is weird. It was an inexperienced DIY install and I thought "home running" where possible would be better, similar to the way you'd wire a home (with AC current). I didn't think about possibly creating an imbalance with different resistances in the wire. Regarding wire size, I'll doublecheck but I think it's 1/0 wire. Seems like that should be ample?


Spent the night connected to shore power last night, just to try to get everything rebalanced before going back into the parks. Reached a peak voltage of 14.44V before I went to bed last night, dropped to 13.65V by morning WHILE STILL PLUGGED IN, continued dropping to 13.47V while I was having coffee, and now is back at 13.65V. I do plan to clean up the wiring, but this seems incredibly bizarre right??


Thanks for the info everyone, much appreciated.

The cable size looks like it’s good for 150A so will be ok if you keep the 2 rows of batteries as the inverter could draw around 200A at full power.

Have a look at the Victron Wiring Unlimited book section 3.3 will give you some good info on wiring up batteries in parallel.

https://www.victronenergy.com.au/upload/documents/Wiring-Unlimited-EN.pdf

As for the voltage readings while charging, who knows what’s going on with the batteries wired like that.

1 Answer
ee21 avatar image
ee21 answered ·

I'm stepping out on a limb a little here, as you have a very different setup than myself.. With that disclaimer being said, I do have some experience building batteries from raw cells, and the symptoms you are describing sound very very similar to what I have seen in my system...


My battery bank is a fully DIY design I made myself, hence it lacks any of the professional finishing of a name-brand LifePo4 unit, which typically have some sort of self-contained BMS, and communication interface (ideally) allowing them to talk to the Victron system.. Mine has a BMS, but no way of communicating with the Victron system to signal "allowed to charge" or "allowed to discharge" unfortunately, so what it does instead if a threshold is tripped, is it uses digital relays to cut connection.


When this occurs, I have observed that the voltage on the other end of the BMS does not simply go to 0, it seems to either drop significantly (just as you describe) to a point that is far below what a lithium battery should be... This is not the actual cell voltage dropping this low, if I were to take a voltimeter and check the voltage on the other side, I would see something much higher (around whatever the cutoff voltage of the BMS was set to). On the opposite end, during charging, you might see the voltage rise wayy to high, to the point of the Victron signaling an over-voltage alarm..


Now I can't say for sure this is what the issue is you are experiencing, but it sure sounds a lot like it. My BMS can cutoff the charge/discharge for a number of reasons, being from a single cell's voltage dropping too high or too low, to the battery as a whole voltage dropping too low or high, or too much current draw, all can cause this to happen.


I would advise you take your battery bank apart and test each piece, put it under a decently high (yet lower than the allowed spec obviously) charge current, and then subsequently discharge current. See if the voltage drops unexpectedly during discharge, or rises unexpectedly during charge... You might have a bad battery... Or more specifically a bad cell within one battery, or possibly defective BMS inside the battery.. This could throw the whole bank into whack potentially when wired together, especially if in series.

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